Historical dictionaries have not yet incorporated prototype theoretical principles, from which singular enhancements might be obtained in historical lexicography. Revisiting diachronic definitions from a prototypical standpoint underlines how salience-based definitions comply more accurately with the cognitive constraints of the human mind. Upon this realization, the paper presents a template for reorganizing historical definitions according to the principles of prototype theory. The resulting definitions depict the semasiological profile of terms in a more transparent way while stressing the mutual interface between linguistic and extralinguistic data and between synchrony and diachrony. At the same time, the paper shows how the theoretical tenets of cognitive linguistics can be put to use in the field of applied linguistics, viz. lexicography.